Accurate marine propellers flow field CFD through anisotropic mesh optimization

2019 ◽  
Vol 29 (9) ◽  
pp. 3148-3168
Author(s):  
Ahmed Abou El-Azm Aly ◽  
Wagdi G. Habashi
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Computational Cost ◽  
Open Water ◽  
Mesh Optimization ◽  
Complex Flow ◽  
Anisotropic Mesh ◽  
Content Type ◽  
Marine Propellers ◽  
Thrust And Torque

Purpose Computational fluid dynamics (CFD) simulation of the flow field around marine propellers is challenging because of geometric complexity and rotational effects. To capture the flow structure, grid quality and distribution around the blades is primordial. This paper aims to demonstrate that solution-based automatic mesh optimization is the most logical and practical way to achieve optimal CFD solutions. Design/methodology/approach In the current paper, open water propeller performance coefficients such as thrust and torque coefficients are numerically investigated. An anisotropic mesh adaptation technique is applied, believed for the first time, to marine propellers and to two computational domains. Findings The current study’s performance coefficients are compared with other previously published CFD results and improvements in terms of accuracy and computational cost are vividly demonstrated for different advance coefficients, as well as a much sharper capture of the complex flow features. Originality/value It will be clearly demonstrated that these two improvements can be achieved, surprisingly, at a much lower meshing and computational cost.

RANS Maneuvering Simulation of Esso Osaka With Rudder and a Body-Force Propeller

2005 ◽  
Vol 49 (02) ◽  
pp. 98-120
Author(s):  
Claus D. Simonsen ◽  
Frederick Stern
Keyword(s):  
Flow Field ◽  
Open Water ◽  
Verification And Validation ◽  
Fair Agreement ◽  
Navier Stokes ◽  
Complex Flow ◽  
Flow Problems ◽  
The Difference ◽  
Propeller Geometry ◽  
Flow Study

A simplified potential theory-based infinite-bladed propeller model is coupled with the Reynolds averaged Navier-Stokes (RANS) code CFDSHIP-IOWA to give a model that interactively determines propeller-hull-rudder interaction without requiring detailed modeling of the propeller geometry. Computations are performed for an open-water propeller, for the Series 60 ship sailing straight ahead and for the appended tanker Esso Osaka in different maneuvering conditions. The results are compared with experimental data, and the tanker data are further used to study the interaction among the propeller, hull, and rudder. A comparison between calculated and measured data for the Series 60 ship shows fair agreement, where the computation captures the trends in the flow, that is, the flow structure and the magnitude of the field quantities together with the integral quantities. For the tanker, the flow study reveals a rather complex flow field in the stern region, where the velocity distribution and propeller loading reflect the flow field changes caused by the different maneuvering conditions. The integral quantities, that is, the propeller, hull, and rudder forces, are in fair agreement with experiments. No formal verification and validation are performed, so the present results are related to previous work with verification and validation of the same model, but without the propeller. For the validated cases, the levels of validation are the same as without the propeller, because the validation uncertainties, that is, the combined experimental and simulation uncertainties, are assumed to be the same for both cases. Based on this, validation is obtained for approximately the same cases as for the without-propeller conditions, but the comparison errors, that is, the difference between experiment and calculation, are different. For instance, the difference between computation and experiment for the ship resistance is generally larger with the propeller than without, whereas the opposite is the case for the rudder drag. Summarizing the results, the method shows encouraging results, and taking the effort related to modeling the propeller into account, the method appears to be useful in connection with studies of rudder-propeller-hull related flow problems, where the real propeller geometry cannot be modeled.

scholarly journals CONTRIBUTIONS TO THE MARINE PROPELLERS HYDRODYNAMIC DESIGN

2014 ◽  
Vol 13 (2) ◽  
pp. 41
Author(s):  
B. I. Favacho ◽  
J. R. P. Vaz ◽  
A. L. A. Mesquita
Keyword(s):  
Control Volume ◽  
Computational Cost ◽  
Momentum Balance ◽  
Marine Propellers ◽  
Energy And Momentum ◽  
Thrust And Torque ◽  
The Mathematical Model ◽  
Low Computational Cost ◽  
Bem Theory ◽  
Good Agreement

The navigation in Amazon region is very important due to the length of navigable rivers and the lack of alternative road network, as well as being a form of transportation costless for the flow of agricultural and manufacturing production. This kind of transportation present social, economic and technological importance for this region. Thus, this work objective to develop a mathematical approach for the marine propellers design, using a formulation for chord and pitch angle optimization, taken into account the equations of mass, energy and momentum balance for the theoretical calculation of thrust and torque relationships on an annular control volume, ie, the mathematical model is based in the Blade Element Momentum (BEM) theory. The proposed hydrodynamic model present low computational cost and it is easy to implement. The results are compared with classical Glauert's theory and the experimental data of the Wageningen B3-50 propeller, presenting good agreement.

Research Analysis and Experiment Study on Flow Field of Hydrodynamic Coupling

2011 ◽  
Vol 418-420 ◽  
pp. 2006-2011
Author(s):  
Rui Zhang ◽  
Cheng Jian Sun ◽  
Yue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Two Phase Flow ◽  
Three Dimensional ◽  
Internal Flow ◽  
Phase Flow ◽  
Complex Flow ◽  
Two Phase ◽  
Operation Conditions ◽  
Hydrodynamic Coupling

CFD simulation and PIV test technology provide effective solution for revealing the complex flow of hydrodynamic coupling’s internal flow field. Some articles reported that the combination of CFD simulation and PIV test can be used for analyzing the internal flow field of coupling, and such analysis focuses on one-phase flow. However, most internal flow field of coupling are gas-fluid two-phase flow under the real operation conditions. In order to reflect the gas-fluid two-phase flow of coupling objectively, CFD three-dimensional numerical simulation is conducted under two typical operation conditions. In addition, modern two-dimensional PIV technology is used to test the two-phase flow. This method of combining experiments and simulation presents the characteristics of the flow field when charging ratios are different.

CFD Simulation of Propeller and Tunnel Thruster Performance

2014 ◽  
Author(s):  
Ping Lu ◽  
Sue Wang
Keyword(s):  
Flow Field ◽  
Cfd Simulation ◽  
Open Water ◽  
Ship Hull ◽  
Hydrodynamic Performance ◽  
Navier Stokes ◽  
Computational Domain ◽  
Flow Features ◽  
Computational Fluid Dynamics Cfd ◽  
Drag And Lift

In the present study, the hydrodynamic performance of a typical North Sea dynamic positioning (DP) shuttle tanker consisting of two main propellers, two rudders, and two bow tunnel thrusters is investigated by solving Reynolds-averaged Navier-Stokes (RANS) equations for a viscous flow. The focus of the numerical simulation is on the performance of propellers/rudders and bow tunnel thrusters considering the hydrodynamic interactions between propellers/thrusters, hull and current. The numerical model includes hull, propeller, rudder, bow tunnel thruster and flow field. First, an analysis of a propeller performance in open water is carried out by calculating the coefficient of thrust, torque, and propeller efficiency. Then, rudders are included in the analysis for the assessment of propeller/rudder performance. The pressure distribution on rudders, rudder’s drag and lift coefficients for different angles of attack, and flow field around the rudder are obtained. The interaction effects between propeller, rudder, ship hull, as well as bow tunnel thruster and ship hull are analyzed by adding detailed ship hull geometry in the computational domain. The tunnel thruster efficiency reduction due to current and ventilation is also analyzed. The presence of current leads to significant changes in the flow velocity and distribution of pressure in the tunnel outflow area as well as significant deflection of the propeller jet emitting from the tunnel. A comparison between Computational Fluid Dynamics (CFD) and model test results of flow features near the tunnel area with various current speeds is presented.

scholarly journals Prediction of Propeller Performance Using Computational Fluid Dynamics Approach

2019 ◽  
Vol 2 (2) ◽  
pp. 185-193
Author(s):  
Nur Amira Adam ◽  
Ahmad Fitriadhy ◽  
W. S. Kong ◽  
Faisal Mahmuddin ◽  
C. J. Quah
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Cfd Simulation ◽  
Computational Simulation ◽  
Open Water ◽  
Water Model ◽  
Thrust Coefficient ◽  
Propeller Performance ◽  
Prediction Approach ◽  
Thrust And Torque

A reliable prediction approach to obtain a sufficient thrust and torque to propel the ship at desired forward speed is obviously required. To achieve this objective, the authors propose to predict the thrust coefficient (KT), torque coefficient (KQ) and efficiency (η) of the propeller in open-water model test condition using Computational Fluid Dynamics (CFD) simulation approach. The computational simulation presented in the various number of rotational speed (RPM) within the range of advance ratio J=0.1 up to 1.05. The higher value of J lead to decrease 10KQ and KT. While the η increased steadily at the lower value of J and decreased at the higher value of J. The results also showed that the propeller with 1048 rpm obtain a better efficiency at J=0.95 with η= 88.25%, 10KQ=0.1654 and KT= 0.0942. The computation result is very useful as preliminary data for propeller performance characteristics.

scholarly journals Investigation of the Unsteady Flow Generated by an Axial Fan: Experimental Testing and Simulations

2005 ◽  
Vol 2005 (3) ◽  
pp. 256-263 ◽  
Author(s):  
R. S. Amano ◽  
E. K. Lee ◽  
C. Xu ◽  
Jianhui Xie
Keyword(s):  
Flow Field ◽  
Unsteady Flow ◽  
Flow Measurement ◽  
Cfd Simulation ◽  
Experimental Testing ◽  
Strain Analysis ◽  
Test Facility ◽  
Axial Fan ◽  
Complex Flow ◽  
Fea Simulation

The unsteady flow measurement of a large axial fan with diameter 1.829m (6 ft) has been carried out. The complex flow field generated by the fan is investigated through experimental testing and CFD/FEA simulation. The results presented in this paper can be divided into three parts. The first part consists of the experimental description of the test facility, velocity measurement, flow-field visualization, and stress/strain analysis of the fan blades. The second part consists of the CFD simulation of the flow field. Simulation is carried out to analyze the flow pattern with and without a radiator attached to the fan casing. The results presented in this paper can be used as a reference for axial fan performance improvement in the future.

A Theoretical Model for Flow Instability Inception in Transonic Fan/Compressors

2013 ◽  
Author(s):  
Xiaofeng Sun ◽  
Xiaohua Liu ◽  
Dakun Sun
Keyword(s):  
Theoretical Model ◽  
Flow Field ◽  
High Speed ◽  
Cfd Simulation ◽  
Flow Instability ◽  
Computational Cost ◽  
Mean Flow ◽  
Transonic Compressor ◽  
Onset Point ◽  
Transonic Fan

This paper applies a theoretical model, which has been developed recently, to calculate the flow instability inception of axial transonic fan/compressors system. After the mean flow field is computed by steady CFD simulation, a body force approach, which is a function of flow field data, is taken to represent the effects of discrete blades on the flow field and duplicate the physical sources of flow turning and loss. Further by applying appropriate boundary conditions and spectral collocation method, a group of homogeneous equations will yield from which the stability equation can be derived. The singular value decomposition method is adopted over a series of fine grids in frequency domain to solve the resultant eigenvalue problem, and the onset point of flow instability can be judged by the imaginary part of the resultant eigenvalue. The present investigation is to validate the feasibility of calculating the stall onset point for single stage transonic compressor. It is shown that this model is capable of predicting instability inception point of transonic flow with reasonable accuracy, and it is sustainable in terms of computational cost for industrial application. It is shown that this model can provide an unambiguous judgment on stall inception without numerous requirements of empirical relations of loss and deviation angle. It provides a possibility to check over-predicted stall margin during the design phase of new high speed fan/compressors. In addition, the effect of flow compressibility on the stall onset point calculation for transonic rotor is studied.

Large-Eddy Simulations of Submarine Propellers

2015 ◽  
Vol 59 (04) ◽  
pp. 227-237
Author(s):  
Elias Balaras ◽  
Seth Schroeder ◽  
Antonio Posa
Keyword(s):  
Computational Cost ◽  
Open Water ◽  
The Body ◽  
Large Eddy Simulations ◽  
Immersed Boundary ◽  
Tip Vortices ◽  
Marine Propellers ◽  
Acoustic Signature ◽  
Large Eddy ◽  
Water Conditions

High-fidelity, eddy-resolving, simulations of marine propellers are challenging due to the coexistence of moving and stationary elements within the computational box, as well as the need to accurately resolve the dynamics of wake structures such as the tip and hub vortices, which have an effect on the acoustic signature of underwater vehicles. Although an isolated propeller in open-water conditions can be simulated in a rotating reference frame, in a computation involving the body of an appended submarine, e.g., the relative motion needs to be properly treated. This increases the computational cost and reduces the accuracy/robustness of typical body-fitted approaches. In this work, an immersed boundary formulation is utilized to perform large-eddy simulations of a propeller in open-water conditions and in the presence of an upstream appendage at zero incidence. In such case, the requirement for the grid to conform to the moving body is relaxed—solution is locally reconstructed to satisfy boundary conditions—and efficient, conservative structured solvers can be used. This enables us to capture the detailed dynamics of the tip vortices and their footprint on the statistics of the wake. The influence of the upstream appendage is also assessed.

scholarly journals Viscous-Inviscid Coupling Methods for Advanced Marine Propeller Applications

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Martin Greve ◽  
Katja Wöckner-Kluwe ◽  
Moustafa Abdel-Maksoud ◽  
Thomas Rung
Keyword(s):  
Flow Field ◽  
Viscous Flow ◽  
Predictive Accuracy ◽  
Computational Cost ◽  
Open Water ◽  
Flow Simulations ◽  
Numerical Effort ◽  
Reaction Forces ◽  
Unsteady Viscous Flow ◽  
Viscous Flow Field

The paper reports the development of coupling strategies between an inviscid direct panel method and a viscous RANS method and their application to complex propeller ows. The work is motivated by the prohibitive computational cost associated to unsteady viscous flow simulations using geometrically resolved propellers to analyse the dynamics of ships in seaways. The present effort aims to combine the advantages of the two baseline methods in order to reduce the numerical effort without compromising the predictive accuracy. Accordingly, the viscous method is used to calculate the global flow field, while the inviscid method predicts the forces acting on the propeller. The corresponding reaction forces are employed as body forces to mimic the propeller influence on the viscous flow field. Examples included refer to simple verification cases for an isolated propeller blade, open-water validation simulations for a complete propeller, and more challenging investigations of a manoeuvring vessel in seaways. Reported results reveal a fair predictive agreement between the coupled approach and fully viscous simulations and display the efficiency of the coupled approach.

scholarly journals The study of typical water header flow structure by LES and RANS

2021 ◽  
pp. 293-293
Author(s):  
Hao Qin ◽  
Bin Wang ◽  
Yun Guo ◽  
Miao Hu
Keyword(s):  
Flow Field ◽  
Flow Structure ◽  
System Analysis ◽  
Cfd Simulation ◽  
Fluid Dynamic ◽  
Rapid Change ◽  
Convergence Criteria ◽  
Complex Flow ◽  
Complex Flow Structure ◽  
Rans Method

Water header is the most common structure in the design of flow system for energy and power system. The complex flow structure could result in some problems when Computational Fluid Dynamic (CFD) simulation is applied in the whole system analysis. The rapid change in velocity distribution of the flow field leads to difficulties to create suitable boundary layer mesh, and the complex flow structure will also make residuals hard to reach convergence criteria. Large Eddy Simulation (LES) is promising to promote these studies, it is more accurate than RANS method and can capture many non-steady state characteristics those RANS method can?t obtain. In this study a typical water header flow structure is investigated by RANS and LES methods. By comparing the detailed flow structures in the results of two methods, the deficiency of RANS method was found. The results of LES can be used to guide the establishment of meshes and the application of time-averaged turbulence models to improve efficiency in engineering. And the asymmetric Reynolds stresses may induce asymmetric flow field in symmetric geometry.

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